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SpaceNut

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kbd512 Light Presurized Rover and Habitat

SpaceNut,

I'd really like to put the light pressurized rover in its own thread because RV'ing on Mars is a general topic and this is a specific proposal.  Feel free to move my posts and responses to its own thread.  I'll stick to ideas about light unpressurized rovers in this thread.

Feel free to move my comments about mission architecture out of this thread and into the Mars Mission Comparisons thread.  GW made comments about mission architecture and I responded.  It's all somewhat OT, but explains why we'd want LPR's for exploration and bases with LUPR's for general utility transportation.

With a roving achetecture there is no reason to go back as its explored, Mars needs roots to allow as well as to  to force continued growth to explore when we stay on its surface long term and this will allow us to not comeback to earth creating a permanent base.

My light and heavy roving mission architectures are all about maximizing surface exploration per mission.  Even Dr. Zubrin has always said that the purpose for going to Mars is because that's where the science is and that's where the challenge is.  Now it sounds like we have an ulterior motive for going, which would be establishing a permanent human presence on Mars.  I'm not in favor of nor opposed to a permanent human presence on Mars, but the mission of NASA is to explore.  Base building is not exploration and in point of fact ISS base building has severely inhibited actual space exploration.

A rover must return at some point for supplies if no cargo drop zones have been created and must go to the nearest MAV to return home. This all creates a disposable achectecture when using a mobility exploration living combination.

My rovers don't need to return to bases or cargo dumps because everything required for crew sustainment is carried in the rovers.  The disposability of the architecture is a matter of practicality and cost.

It's far easier to send two or three more Falcon Heavy with the entire surface exploration architecture (one rocket carries all four rovers and the other two rockets deliver the MAV's) than it is to refurbish the rovers on Mars and no surface time is lost to that endeavor.  The roving exploration concept is simple, practical, and affordable in comparison to base building alternatives.

Maintaining a regular launch cadence using affordable rockets is a substantial part of what makes my mission architecture so practical.  Launching Falcon Heavy and Vulcan 3-5 times per year is well within NASA's human space flight budget, keeps SpaceX / ULA / NASA busy with delivery of human space flight hardware, and operations have a minimal level of complexity.  Without the requirement to maintain a $3B a year fixed cost launch vehicle operations and development program, there is sufficient funding to allocate to payload development.

Any first as well as second will return to current infrastructure left behind....and that is when the small pressurized rovers should be ready for dropping to the bases for larger area of exploration. That makes 3 mars cycles (2yrs +7 weeks) which will be pretty close to the decade number for more R&D to have completed more work towards getting hardware mature for use.

Small pressurized rovers can be ready before a Mars base is ready.  All the supporting hardware development program requirements are much lower.  EDL is easier because the payloads are much lighter, no super heavy lift vehicle is required to deliver the surface exploration hardware, power generation and storage requirements are the same, and mission flexibility is much higher.

My assertion is that building and maintaining a base is a substantially more difficult and expensive proposition.  With enough time and money, anything is possible, but my mission architectures have revolved around what's most practical from a funding and technology availability standpoint.  There's no "science fiction" involved with delivering a 2.5t payload to Mars.  Delivery of 10t for the surface exploration architecture is imminently reasonable and affordable.

Thanks for the nasa links from both of you as that shows where we are with needed technology. When we read them plus find questions as to how long, how much, whats required to make it work; one can see we still need more work on developement....

The assertion has been repeatedly made that we can go to Mars with the technology we have or had decades ago.  I think that apart from ECLSS, that's true.  Our 1970's era rockets were good enough and our 1970's era spacecraft were good enough.  However, ECLSS technology of the time was back in the stone age compared to what we have today and will have in the near future.  Our data storage and transmission technologies of that era were laughably poor compared to what we have today.

Anyway, if we're dead set on building a base on Mars, it will be another two decades or more before NASA can do that.  How long do you want to wait?

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

quote:  "Once the astronauts / prospectors have located a region that is reasonably rich in water, minerals, and ores, then we can build a base there.
I want to build a base on Mars, but I don't want to build a base on Mars for sake of having a base on Mars."

The purpose of having a base there is not simply to have a base there.  The base must serve some greater purpose than its mere existence or its existence will be questioned by Congress and probably never built as a result.

The unstated presumption behind that notion is that government will send more than one expedition to Mars.  But that presumption is there.  It is the wrong presumption to make.  I have said for a long time now that the government (any of them) very likely will send one and only one expedition,  period,  end of issue.

If we build a base more than one expedition will be sent?  Why?  Congress can pull the plug any time it wants to, no matter the cost.  If NASA turns this program into some insanely expensive variation on ISS, the result will be no different irrespective of architecture.  The STS, SLS, ISS, and Orion programs have two things in common.  Both were or are an enormous drain on NASA's limited resources and all have produced very little result, with respect to actual space exploration.

So:  how do you accomplish the exploration for a suitable site,  plus the establishment of the core of that base,  all in one mission?  If that core of a base exists,  the it becomes far more likely that a Spacex might then return to it and continue the work.

SpaceX has the billions socked away for that?  Unlikely.  A base that's never built during a mission that never happens because it costs too much won't help them at all.

But hoping the government will follow through like that is a very,  very,  very futile hope.  The decades of going nowhere but LEO since Apollo are the proof.  QED.

Then the many tens of billions required to use SLS, Orion, and non-existent in-space propulsion, EDL, surface habitats, and more is even more futile.  Devise an architecture that is expensive and complicated enough and the result is that the mission never happens.

There were four incarnations of SLS (ALS, NLS, Shuttle C, and Ares V) that failed to deliver any results because the programs cost too much.  SLS will be the fifth attempt at the impossible (making the world's most expensive reusable hardware affordable by throwing it all away after every launch).  It's outright ridiculous on the face of it and no cosmetic makeover that changes the name of the program is going to change that.

That is why I keep saying what I do about the architecture of that one-and-only government-funded mission.  Base in LMO,  and send down very large one-stage reusable landing boats to explore multiple sites with men,  for about the 1st half of their stay there.  That will identify the best site,  at which everybody goes down during the 2nd half of the stay,  and establishes the core of that base.

If delivery of four light trucks and two MAV's is too difficult then using a reusable rocket on Mars, which is something that's never been done on Earth, is even more improbable.

Sure,  it's a lot more thrown mass.  Sure,  it's a lot more expensive.  Sure,  you are talking about landing boats too big to fling to LEO even with SLS.  But as near as I can tell,  there is simply no other way to do what needs to be done,  in that one-and-only mission.

I think what you're proposing is so difficult and expensive that it won't be done within the next twenty years and maybe not even in the next thirty years.

Fail to do all of that,  in that one-and-only mission,  and it very quickly devolves into nothing but an Apollo flag-and-footprints stunt on Mars (stingy Congress will force that outcome).  If that happens,  then it'll be the best part of another century before private enterprise decides to go in any major way. 

Be warned..

GW

Congress is stingy with funding because for the better part of the last three decades NASA has come up with one infeasible solution to human space exploration technology problems after another.  There's no explanation as to why CL-ECLSS isn't current technology.  The agency was too involved with LEO base building to develop the technologies that were actually required for real space exploration.  To this day, closed loop life support, adequate in-space propulsion, and affordable (meaning easily reusable) launch vehicles are still developing technologies.  There's no cohesive plan behind any part of the human space exploration program.  It's all "Let's throw some money out there and see what sticks."  Well, I got news for everyone.  The only thing that "stuck" was the bill.

We can prove that we can go there, explore, and come back using the architecture that I've laid out.  It's the least technologically demanding and most affordable mission architecture I've seen thus far.  Virtually every other plan involves obscenely expensive super heavy lift rockets to deliver payloads that Saturn V would have had difficulty delivering or kamikaze missions.  Apart from life support technology development, little other technology development is required to do the mission I've laid out.  We already have the propulsion, communications, energy production, energy storage, and EDL technology to do what I want to do.  Even if it's "flags-and-footprints", which is most definitely not the case with my mission architecture, then some human exploration of Mars is better than no human exploration of Mars at all.

I think it's going to be at least another fifty years before private enterprise does anything in space that doesn't provide a clear economic incentive to do so and that's with or without public funding for space exploration.

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

I want to appologize as the above posts probably are not all that needs to be there to start the topic....

So the LPR is a habitat roving archecture and exploration of science for minimal fund tool to go to mars with.

The rover from other posts is a one person self contained transport and habitat that will have a gross profile once filled to not be more than 20 mt, with food, water, life support, power system, waste storage for processing and science experiments and other such that allow for man to do work.

What about health care as we do not know what the lesser gravity will do for a non exercising astronaut....I would think that we would need a plan and equipment for the rover to ward off any issues. With the plan we now have less distance that we can cover in the rover habitat by virtue of stopping to eat, exercise and to do science....

ISS maximum food storage volume and mass allowances per person per day:

6570 cubic centimeters -> 3.285 cubic meters per person for 500 days

2.38 kg -> 1190 kg per person for 500 days (I think we can get this down to 1000kg with improved packaging and high energy breakfast bars)

Edit: According to this NASA Sustaining Life article, 915kg of food is required for 500 days, so our food and water are roughly 1290kg of our 1500kg payload.  That leaves 210kg for other stuff (most likely spare rover parts, tools, and electronics).

Rover Habitation Unit Dimensions:

Habitation Module: 2m D x 5m L (could be reduced to 2m D x 4m L, but it'd be pretty cramped)
Airlock: 1m D x 2m L

Rover Base Unit Dimensions / Volumes / Masses (dimensions do not include the attached rocker bogie assemblies):

Core Unit: 4m L x 2.5m W x .5m H

Core Unit Cargo Volume: 5 cubic meters

Cargo Volume Use Breakdown:

3.285 m3 - Astronaut Rations

.375m3 - 3m L x 2.5m W x .05m H - 375L (for fresh and grey water tanks and SPE protection - astronauts hide in a ditch under their rover and attach power/air/water umbilicals to the rover)

.0738 m3 - GAIA HE 602030 NCA cells split into two 10kW battery packs containing 50 cells each (won't be used because energy density is only 132Wh/kg, yielding 151kg for 20kWh capacity, but gives an idea of the upper limit to battery weight and volume; Panasonic NCR18650B cells provide 243Wh/kg, so 82kg for 20kWh capacity although in all reality we'd just add capacity up to about 100kg or so)

.06627 m3 - 4 MOXIE oxygen generators (I really need the mass for MOXIE, anyone have it?)
# m3 - 2 CL-ECLSS (anybody know what type of ECLSS is required for a 2m x 5m inflatable cylinder with a 1m x 2m airlock attached to it?)

I don't know what volumes and masses are required for tools or life support, but it's probably a safe bet that the base unit can be shorter or narrower than my stated dimensions because we're only up to 3.74 m3 and have 1.26m3 worth of volume remaining.  If we have substantial volume remaining after the ECLSS and water generator hardware have been accounted for, then we can shrink the base unit height to reduce volume and weight.

If anyone can help spec this vehicle out, feel free to contribute.

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

Y'all are correct to refer to the depicted designs as busses.  Like tanks,  when a thing gets too big,  you cannot successfully run it off-road.  There are as yet no paved highways on Mars.

Agreed.

Why not build an open 4-wheeler like the lunar rover,  but with 4-6 seats (that depends on intended surface crew size),  so a little bit larger than the lunar rover,  but only a little bit larger.  Simple battery electric propulsion,  just like the lunar rover.  At worst,  6 wheels like the robot rovers that have been successful.  I'd use knobby rubber off-road tires and apply electric heat to the rims to keep the tires from getting too cold.

The unpressurized rover provides no operational advantages over a light pressurized rover.  Are you going to travel inside a deployed tent atop an unpressurized rover or trailer or wear your space suit 12 hours a day?  I could be wrong, but that doesn't seem very practical to me.  With respect to heating the rubber wheels, that was my first thought.  What are the power requirements to do that?

Bring a powered jack and some spares,  too.  You'll need them:  those rocks are very sharp.  Drag metal through rocks,  and eventually the rocks always win.  You need resilience and "give" to your wheels to cope with that.  (Better think about changing tires in your spacesuit design,  too!)  This is months on the surface,  not a day or three like on the moon.  You will have a flat to fix.

The only power tool on my light rover design is a drill used for scientific purposes.  Each rover will carry a bottle jack and a spare wheel or two, but only hand tools will be used.  The bolts connecting the wheel to the suspension arm will be turned by hand.

Here's an idea:  add a string of trailers to fit the task at hand.  One trailer might have a pressurized inflatable "tent" and life support supplies exceeding the rover range by a wide margin.  Another might have fuel cell supplies and solar panels,  a mixed-source power trailer for extended-range operation.  The third might be a portable drill rig for deep-drilling.  And so forth.  Pull one or all of them when you need them,  don't hitch 'em up when you don't.

Every vehicle needs power and habitation capability.  Structural mass for cargo storage must be minimized using advanced materials and reasonably intelligent vehicle design.  Dragging trailers behind a prime mover doesn't make the math involved with delivering the required tonnage any easier and needlessly complicates travel.

I want to deliver four light trucks to Mars because that's all that's really required for initial surface exploration.  Any habitation more extravagant than a light pressurized rover comes from the investment of more funding for improved habitation and purchases of additional launches to deliver a habitation module.

If there's available funding for additional hardware to increase exploration returns, perhaps a base unit equipped with LOX/LCH4 tanks and ISPP plant and a base unit equipped with a methalox powered drill can be sent for extraction of core samples.

You'll need the power in the rover to pull trailers off-road through the rocks and dirt.  It will be slow going,  very much like a farm tractor,  with low and really-low gears.  Designing mission objectives and plans for 30+ km/hr speeds is utter nonsense.  Much of Mars is way too rough for that.

My light truck has electric hub motors that permit speeds of 50+ km/hr over level and smooth ground because 10kW of power is sufficient for that purpose in a vehicle that only weighs .95t fully loaded.  Gearing implies the addition of a heavy mechanical device (transmission) that adds mass and another potential mechanical failure that will be more difficult to repair or replace than a hub motor.  I don't believe a transmission is required, nor even desirable, and adding a transmission increases the mass of the vehicle and thus the mass of the suspension.

The fact that the rover is capable of 50+ km/h doesn't mean that that's a recommended travel speed.  There's no desire on my part to travel at speeds that the terrain won't permit.  The burst speed capability is useful for quickly arriving in the landing area after the astronauts land in their capsule and quickly arriving at the scene of a vehicular accident.  More importantly, the slight excess of torque and power over what's minimally required provides the gradient climbing capability that off-road vehicles require and also permits retrieval or towing of stuck or disabled vehicles.

Smaller,  simpler,  lighter,  and way-to-hell-and-gone more versatile that modular way with a tractor and a selection of trailers.  That last (versatility) is really the most important advantage,  after all,  because history teaches we will encounter the unexpected / unanticipated. 

Going modular,  splitting off different functions into various add-on trailers,  sure beats trying to design everything imaginable into one single item. 

GW

Chariot and ATHLETE integrate too many tools and technologies for surface exploration into a single vehicle that must also provide habitation.  The high structural mass and mechanical complexity of Chariot and ATHLETE are exactly what I want to avoid by using simple light electric trucks.  Each vehicle is sized to carry one quarter of the consumables required to support a 500 day nominal surface stay with 4 crew members, assuming ISRU for oxygen and water.  Each vehicle has ECLSS intended to support one or two crew members, so loss of a vehicle through mechanical failure is not equivalent to loss of crew or mission.

The solution you're proposing adds back structural mass in the form of towed vehicles.  With a loaded mass of 2.5t and loaded weight of .95t on Mars, the vehicles I propose are so light that trailers aren't required.  The proposal to not tow trailers if they're not required for a particular expedition is functionally equivalent to tethering the astronauts to a base or supply dump.  I don't want the astronauts tethered to a base or supply dump.  I want real mobility.  I think the best way to achieve that is through the use of multiple identical and appropriately sized trucks.

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

Moxie is intend to prove out whether we can count on insitu propellant production before sending a manned flight.

A full-size CO2 acquisition system requires 8 kg/hr of martian atmosphere, ~0.14 m3/s at 7 mbar. Preliminary mission models suggest that more than 30 metric tons of oxygen will be needed as the oxidant for this ascent, representing about 78% of the propellant mass in a CH4/O2 propulsion system. This would translate into 400 metric tons in Earth orbit – requiring 4 to 5 heavy lift launches. Such a full-scale system would produce roughly 25-30 metric tons of O2 during the ~17-month period between arrival of the ISRU system and ascent vehicle on Mars, and the decision to launch the human crew at the next launch opportunity. This requires a production rate of approximately 2.2 kg/hr. An assembly of 100 stacks, each containing 20 MOXIE-sized cells, would produce >2 kg/hr of O2 with an energy investment of ~12 kW.

The unit that is being sent is a scalled down model of electrolysis....

MOXIE is a 1% scale model of an oxygen processing plant that might support a human expedition sometime in the 2030s. MOXIE will produce 22g/hr of O2 on Mars with >99.6% purity during 50 sols. The maximum mass allowed for internal payloads was defined as 15 kg, and the maximum volume was 23.9 cm x 23.9 cm, x 30.8 cm (9.45’ x 9.45’ x 12.2’). The Mars 2020 PIP states that the heritage power/energy system for the Curiosity rover provides approximately 1000 watt-hours (W-hrs) per Mars day (sol) for all surface operations, and that the rover will provide between 100 and 600 W-hrs per sol for payload operations with a voltage between 22 and 36 volts.

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

http://www.nasa.gov/pdf/146558main_Recy … _10_06.pdf

0.84 kg per person per day

http://www.nasa.gov/pdf/570243main_Oxyg … HEM_ST.pdf

The ISS is designed for a six-person crew, but until recently, the oxygen supply would only allow for three crew membersat a time. In 2007, a new Oxygen Generator System (OGS) was activated in order to increase the ISS crew capacity up to its six person design. During normal operations on the ISS, approximately 23 liters of water per day is used by the OGS with a constant current of 50 ampere to each electrolytic cell in the OGS system. The temperature on the ISS is 298 K and the atmospheric pressure is 1 atm.

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

There is a second method that requires compression to make Oxygen which must fit into the same form factor as the other one did.

Called the Mars Atmosphere Resource Verification INsitu or MARVIN, instrument will incorporate three subsystems to measure the atmosphere, separate carbon dioxide (CO2) from the Mars atmosphere, pressurize the CO2, and make oxygen (O2). The expected temperatures in the Mars atmosphere range from about -128°C to +50°C while pressures vary from a few hundred Pascal to 1.3 kilopascal (kPa). Mars atmospheric temperature of 210 K (-63°C), the cryocooler will provide 4 watts (W) of cooling with 40 W of power. In the CO2 Collection mode, the Integrated Cryogenic Extraction of CO2 and Utilization By Expansion (ICE CUBE) subsystem is designed to accept filtered or unfiltered Martian atmosphere, freeze CO2 on a cold head chilled to -123.15°C (150 K), the triple point of CO2 at Mars atmospheric pressure, and reject nitrogen, argon, and other minor components from the atmosphere except for the small amount of water vapor present.

The purpose of the ICE CUBE subsystem is to separate CO2 from the Mars atmosphere at low Mars surface pressures, and provide pure CO2 to the Precursor Reactor for Oxygen Production (PROP) subsystem at the pressure and flow rate needed to produce O2 at 0.02 kg/hr for one hour. Solid Oxide Electrolysis-Embedded Sabatier Reactor (SOE-ESR) with the SOE cell uses an electrolyte made of a nonporous ceramic oxide, such as yttria-stabilized zirconia (YSZ), which conducts oxygen ions at elevated temperatures (750°C to 850°C).

RobertDyck

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Re: kbd512 Light Presurized Rover and Habitat

MARVIN? ICE CUBE? You're kidding, right? For one thing, the triple point of CO2 is about 5.2 atmospheres of pressure. Triple point is defined as the point were solid, liquid, and gas meet. Liquid cannot exist below that pressure, so heating a solid will cause it to sublime directly to gas.

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

So with water recovery and insitu uses from 2 sources of Co2 input I think that gives the rover design plenty of backup for oxygen and fresh water from the reaction with methane loss of hydrogen of which I hope the moisture captured in the Co2 input cooling process is enough to offset its loss.

http://www.freesunpower.com/system_sizing.php

This tool will help to solve for the powered used in a not driving mode for solar panel count and batteries to support that feature of daily roving in exploration mode. In the rovering mode we will need more power and panels even if we do not need to add anymore batteries.

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

Mars Atmosphere Resource Verification INsitu

http://ntrs.nasa.gov/search.jsp?R=20140009943

http://sbir.nasa.gov/content/situ-resou … processing

http://ascelibrary.org/doi/abs/10.1061/ … 412190.021
Martian Atmospheric Dust Removal for ISRU Gas Intakes Using Electrostatic Precipitation

http://planetaryprotection.nasa.gov/fil … ers.V2.pdf

IanM

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Re: kbd512 Light Presurized Rover and Habitat

Here's some quick math about the energetics of forming O2 from CO2. A reaction is favorable if and only if its change of Gibbs Free Energy, or DG0, is negative. DG0 is defined as T*DH0-DS0, where DH0 and DS0 are the changes of enthalpy and entropy, respectively, and T is the temperature in Kelvin.

At presumably standard conditions, the DG0 of:
2C(s,graphite) + O2(g) --> CO2(g)
is -394.6 kJ/mol (http://www.wiredchemist.com/chemistry/d … -inorganic).

We want the reverse reaction, that is to say:
CO2(g) --> O2(g) + 2C(s,graphite)
, whose DG0 at such conditions is 394.6 kJ/mol, which is positive and thus makes the reaction not favorable at such conditions. The DH0 and DS0 are fixed (at 393.3 kJ/mol and -213.8 J/molK, respectively), but the temperature is variable. Converting the DS0 to be -0.2138 kJ/molK for unit purposes, we thus need to satisfy the following inequalities to make the reaction favorable:
393.3T + 0.2138 < 0
393.3T < -0.2138
T < -5.44 * 10^-4 K,
which is not only negative and thus impossible, but even if positive would be pretty close to absolute zero. As such, a direct sublimation is unfeasible, and perhaps CO2 should beget O2 by means of more energetically-favorable intermediate reactions.

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The Earth is the cradle of the mind, but one cannot live in a cradle forever. -Paraphrased from Tsiolkovsky

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

The atmospheric pressure on the Martian surface averages 600 pascals (0.087 psi; 6.0 mbar), about 0.6% of Earth's mean sea level pressure of 101.3 kilopascals (14.69 psi; 1,013 mbar). It ranges from a low of 30 pascals (0.0044 psi; 0.30 mbar) on Olympus Mons's peak to over 1,155 pascals (0.1675 psi; 11.55 mbar) in the depths of Hellas Planitia.

Expressed as 0.006 Atm so to get to 5.2 Atm we will be compressing mars roughly 867 times for any volume to end up with just 1 volume of liquified Co2. So while it would work the amount of energy and time frame is to long to electrolysis the oxygen out of it....

600 pascal is 61 kg/m^2

IanM

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Re: kbd512 Light Presurized Rover and Habitat

a direct sublimation

My bad, I meant the opposite, the direct deposition of graphite in the reaction.

Also, there is potential for research of electrolysis of CO2 for many uses such as fuels, so it could be used also for that purpose: https://acswebcontent.acs.org/prfar/201 … 10782.html.

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The Earth is the cradle of the mind, but one cannot live in a cradle forever. -Paraphrased from Tsiolkovsky

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

Mathematical Analysis of High-Temperature Co- Electrolysis of CO2 and O2 Production in a Closed-Loop Atmosphere Revitalization System

IanM

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Re: kbd512 Light Presurized Rover and Habitat

Interesting. Looks like we can have the best of both worlds!

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The Earth is the cradle of the mind, but one cannot live in a cradle forever. -Paraphrased from Tsiolkovsky

SpaceNut

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Re: kbd512 Light Presurized Rover and Habitat

Series Bosch System Development

Compact and Lightweight Sabatier Reactor for Carbon Dioxide Reduction

THE REVERSE WATER GAS SHIFT PROCESS

The Bosch Process - Performance of a Developmental Reactor and Experimental Evaluation of Alternative Catalysts

kbd512

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Re: kbd512 Light Presurized Rover and Habitat

SpaceNut,

Thanks for the links.  Like IanM said, very interesting.

Some more random rover thoughts:

If it's not already apparent, power consumption is the most critical limiting factor in the LPR concept.  The Panasonic NCR18650B cells have a power density of 243Wh / kg.  With only 100kg mass budget allocated for energy storage, we're limited to about 20kWh of power storage.  Each cell in the pack must have its own enclosure to prevent rupture of an individual cell from destroying adjoining cells.

The two 10kWh packs are affixed to the front and rear of the base unit, must be astronaut removable and replaceable, and so may not be excessively large or heavy.  A small woman, perhaps no more than 45kg, must be able to lift and replace the battery packs by hand.  On Mars these packs will will weigh around 23kg each.  It's relatively low to the ground and two large handles that lock the pack in place are provided for grasping, but it's still not an easy lift and the astronaut will be encumbered by a space suit.  If battery pack replacement proves to be a significant problem for the astronauts due to the weight of the packs and mechanics of the lift (packs intended to lock into place like toner cartridges in laser printers using rollers), then we're going to use four 5kWh packs.  The general idea is to co-locate power storage, vehicle electronics, life support, and motors to minimize wiring.

If you need a visual that illustrates how this core / base unit is laid out, think of the Tesla sedans.  Instead of the "skate board" storing batteries, the "skate board" holds the fresh and grey water tanks, with a total capacity of 375L.  Storing the water here is intended to reduce the vehicle's CG height and provide SPE protection by hiding under the vehicle and using umbilical panels (four per vehicle, with each located on a quarter panel).  Immediately above the water tanks are the batteries, life support, electronics, and food storage.  This configuration maximizes radiation protection under the vehicle, minimizes the mass of metals in the vehicle in the form of systems components so as to minimize secondary effects from GCR, and reduce overall mass and volume.

The habitation unit atop of the base / core unit is space suit material and is a simple cylinder 2m in diameter and 5m in length.  This could be reduced to as little as 4m to decrease pressurized volume, but the vehicle would be rather cramped and 5M is essentially the length of a Chevrolet Tahoe.  The airlock really has to be 1M by 2M so that both astronauts can exit at the same time.  The vehicle has articulating suspension and "kneels" for egress by lowering the rear suspension arms and raising the front suspension arms so that the astronauts can simply slide down the airlock and then the base of the airlock hatch is right above.  The astronauts can essentially crawl/slide out.  No steps are required, so it's not possible to slip and fall.  The advantage to this arrangement is that an injured astronaut can be carried back in a flexible stretcher by two astronauts for loading into the vehicle without tools or specialized hardware.

Instead of a hard connection to the base unit, all connections are flexible.  The core unit lashes to the base unit using six kevlar or nylon straps woven or sewn into the kevlar shell of the habitat.  This feature is intended to absorb bumps and vibration, maximize contact surface area between the two units because the straps are really wide and use tension adjustment, and minimize the complexity of habitat module removal.  Depressurize the habitation module and airlock, unlock the interface rings for the toilet, life support, and food prep stations and the entire module can be removed for replacement or swap.  If that's not feasible, then a hard connection has to be devised that permits easy removal of the habitat module.

There is a rather large viewing port built into the front of the vehicle that is nothing more than a polycarbonate or lexan window (1.5M to 1.8M in diameter so the driver can get a really good view of the terrain ahead).  The astronauts sit in fabric seats suspended inside the vehicle with bungees.  This is intended to absolutely minimize mass and volume of the seats and to make the seats removable for nap time.

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: kbd512 Light Presurized Rover and Habitat

Glad you are back to talk about the thoughts on the design content needed to take a single astronaut for the 500 day trip around mars.

We need a Mars base to live. What's the alternative? Just a rover? No way you can put everything you need to live in a rover. This discussion thread says "Light weight rover for Mars", not heavy rover.

Rob,

You need oxygen, food, water, and shelter to live.  Some would say you also need human companionship.  Four humans and four pressurized vehicles provide all of that.  It's not fancy, but it's functional.  Should we engineer solutions that relatively inexpensive commodity rockets can deliver or wait another ten years to complete development of an insanely expensive rocket that won't be launched more than once or twice a year, assuming it isn't killed off by the next political administration.

If we have four seperate rovers for a mission then they could be spaced appart in a parrellel path to scout out even more territory in exploration mode.

I agree that we need to make things as light in mass as possible to allow for the EDL envelope to not need bigger and heavy solutions to land on mars.

I am thinking since the battery box will be outside of the temperature controlled climate of the inside of the rover that we will need some of those apollo heat pellets for the compartment to keep them from seeing temperatures that would cause them to freeze when we are setting idle to recharge them.

We will need to make sure that the rover can tolerate the number of times that we will be decompressing to go out side to be able to lay hands on mars....I am not sure if we can do a partial or full inflateable design with that in mind even thou it would save about 30% in mass over that of a hard can design.

Still trying to understand the visuals on what the rover would look like but thats me.....

I agree that power will need to be the most dependable and able to give all the wattage to charge the batteries. But what is the night time idle power requirement versus when we are moving as it may reqire a day to rebound to a full charge before moving again from a stopping point.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: kbd512 Light Presurized Rover and Habitat

You meantioned some other technologies for battery design, started to look at what they are and can they be fast charged so as to see if we can use solar to do the job.

Ya Mars will not have many of these signs...

http://www.popularmechanics.com/cars/g7 … kthroughs/

https://en.wikipedia.org/wiki/Electric_vehicle_battery
Travel range before recharging

https://en.wikipedia.org/wiki/Charging_station
Charging time for 100 km
Renewable electricity and RE charging stations

Sure we re not driving a Volt but it does illustrate what size is needed.
http://cleantechnica.com/2012/08/26/sol … -launched/

Simular to an all EV use just not driving so fast....
http://media.gm.com/media/us/en/chevrol … /2014.html

It uses no gasoline, yet its GM-built motor and drive unit deliver 400 lb.-ft. (542 Nm) of instant torque, a top speed of 90 mph and a 0-60 time of less than eight seconds.

Storing that energy from the charging process and the vehicle’s regenerative braking capability is a 21-kWh lithium-ion battery pack. Three available levels of recharging capability include the industry’s first use of the recently approved SAE combo charger for DC fast charging, which charges 80 percent of the battery in just 20 minutes.  Spark EV’s 82 miles (130 km) of range.

Spark 1LT is generously equipped and includes these and other standard features:

■120V onboard charger
■240V charging capability
three levels of recharging for the Spark EV:

■AC 120V charging – A 120V onboard charger and charge cord are standard. Plug in the cord into a conventional household outlet and the Spark EV is fully charged in less than 17 hours.
■AC 240V charging – This requires a dedicated 240V charging station and reduces recharging time to less than seven hours.
■DC fast charging – Later in the model year, buyers may select this optional feature that permits the car to be charged using an SAE combo DC fast charger, which charges the battery to 80 percent of its capacity in 20 minutes.

Any Mars recharging from solar is going to be twice if not 3 times as large to preform the same task of recharging the batteries.

http://www.plugincars.com/eight-tips-ex … 07938.html

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: kbd512 Light Presurized Rover and Habitat

Something that has been put forth before was to have drop zone cargo landers for resupply that would lighten the rover as less of the life support conditions would need to be met as we would be stopping at these sites to replentish some of what we would need rather than hauling it all from the get go...

SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: kbd512 Light Presurized Rover and Habitat

As ,uch as the drop zones would work the need for cleaning the Co2 out of the air would still be needed. Post from the other topic....

I think NASA is already hard at work here, but what's the primary advantage of silver oxide sorbents over other technologies?  Is it simplicity, cost, developmental status, or a combination of all of some or all of those?

How much power does the microwave oven require to bake the silver oxide spheres to revitalize the sorbent and how long does the process take?

The advantage of silver oxide is that baking completely removes CO2. Trying that with LiOH doesn't work, you only get a fraction of sorbent capacity back. And after only 3 cycles, you don't get anything back. Amine also bakes completely, so you can recycle amine any number of times. The problem with amine paste painted on styrofoam beads is that you have a giant bag to carry. Low mass, but completely unwieldy. One possibility for a Mars rover is to use liquid amine, the same stuff used on nuclear submarines. Not safe in zero-G, but does work when there's gravity to separate liquid from air.

I have a copy of the NASA contractor report, purchased from the NASA technical report server. Dated August 1996.
Document ID: 19960045813
Accession Number: 96N32683
Report/Patent Number: NASA-CR-201945, NAS 1.26:201945, URC-80647
Contract/Grant/Task Num: NAS2-14374

A very similar paper by the same authors was published by SAE, dated July 1997. So you can read it yourself, click here...
Microwave-Powered Thermal Regeneration of Sorbents for CO2,Water Vapor and Trace Organic Contaminants

Molecular Sieve 5A also worked, although required higher temperature to regenerate, and it absorbed/regenerated water. Carbogenic Molecular Sieve also worked, and didn't absorb water, although it required even higher temperature to regenerate. If you want to route CO2 to a Sabatier Reactor, then you don't want a composite sorbent that can sorb moisture or organics.

The carbogenic molecular sieve material (0.52 g) received from NASA's JPL was also evaluated as a CO2 sorbent. Initial tests with this material indicated an extremely high heat-up rate, actually melting the glass wool end plug. It is noteworthy that the softening point for borosilicate glass is ≈7:00°C. This temperature was apparently achieved inside the packed bed, while the indicated exit gas temperature never exceeded 92°C. A subsequent sorption/desorption cycle indicated a 1% bed weight CO2 loading. It is not known whether the performance of this material was adversely affected by temperatures ≥ 700°C achieved during the first microwave desorption. Insufficient material was available to continue this investigation.

kbd512

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Registered: 2015-01-02

Posts: 7,853

Re: kbd512 Light Presurized Rover and Habitat

Glad you are back to talk about the thoughts on the design content needed to take a single astronaut for the 500 day trip around mars.

I was sick (still sick) and had family / work stuff to take care of, but I'm back.

If we have four seperate rovers for a mission then they could be spaced appart in a parrellel path to scout out even more territory in exploration mode.

That's what I was thinking.  The single file convoy travel mode was merely an idea to ensure that MTVL type heavy rovers running over caves didn't damage or destroy every rover in the convoy.  These rovers are quite light in comparison to my MTVL solution.

If there was a workable method to land 20t rovers on Mars, I would recommend landing a 20t base habitat there first.  The base habitat would serve as the supply depot.  Even if it's possible to do all that, I still want light pressurized rovers that can travel at speeds faster than the heavy pressurized rovers were intended to travel at.

Either way, the mobility that pressurized rovers provide make a lot of exploration possible that a habitat and unpressurized rover solution simply does not.  If a stationary habitat and unpressurized rover is what NASA ships to Mars, I'm pretty confident that the astronauts will never travel further than a few hours from their base.  That's anathema to actual surface exploration.

All the robotic rovers on Mars haven't covered as much ground as my rover solutions would cover in a day and those rovers have been on Mars for years.  The notion that we've done a lot surface exploration with our robots on Mars is just laughable.  We've learned quite a lot from those robotic rovers, but they've literally scratched the surface and nothing more.

I agree that we need to make things as light in mass as possible to allow for the EDL envelope to not need bigger and heavy solutions to land on mars.

I firmly believe that single launch delivery of payloads with modest mass is the way to make human exploration of Mars affordable and practical.

I am thinking since the battery box will be outside of the temperature controlled climate of the inside of the rover that we will need some of those apollo heat pellets for the compartment to keep them from seeing temperatures that would cause them to freeze when we are setting idle to recharge them.

The battery cells are in insulated composite boxes and produce heat in operation.  The robotic rovers are tiny things that use a lot of aluminum in their construction.  It's hard to keep a metal box warm on a frozen planet.  The engineers who build these things need to absolutely minimize the use of metals.  I have no idea whether or not RHU's are absolutely required to keep the batteries and electronics warm.  That's an engineering question that comes down to actual power usage for warmth at night.

We will need to make sure that the rover can tolerate the number of times that we will be decompressing to go out side to be able to lay hands on mars....I am not sure if we can do a partial or full inflateable design with that in mind even thou it would save about 30% in mass over that of a hard can design.

The habitation module really doesn't go through many compression / decompression cycles in a typical mission.  It's inflated before or after the astronauts arrive and then stays inflated through the entire mission.  The only reason to deflate it prior to the end of the surface exploration mission is the scenario where the habitation module on one vehicle is damaged and the base unit from a different vehicle is damaged.  Then it is necessary to decompress the habitation module to swap it.  That's an unlikely scenario, but we've engineered the solution to that problem into the vehicles if it happens.

The airlock, on the other hand, will experience at least 4000 compression / decompression cycles in a typical mission.  The airlock may require the use of composites to achieve the required life expectancy.

Still trying to understand the visuals on what the rover would look like but thats me.....

Try to visualize a cylindrical muffler lashed to the top of a skate board.  Instead of an intake pipe, the front of the muffler has a large hemispherical lens nearly equivalent to the diameter of the muffler so the astronauts can see easily where they're going.  The muffler's tail pipe is the airlock that the astronauts use for ingress / egress.  Unlike a skate board that has wheels directly under the deck, the suspension arms stick out on the sides.  The skate board / base unit is nothing more than a composite box.  Aerodynamics aren't a consideration at the speeds achievable with the atmospheric pressures present on Mars.  Anything fancier than a box is simply not required.

This illustrates what the base unit will look like (except that the suspension is not connected to the front and rear of the base unit, it's connected to the sides):

Gila Board Off-Road Skate Board

This illustrates what I meant by articulating suspension arms to allow the rover to raise / lower / tilt the habitat to permit easy egress through the airlock:

BMW Street Carver

I agree that power will need to be the most dependable and able to give all the wattage to charge the batteries. But what is the night time idle power requirement versus when we are moving as it may reqire a day to rebound to a full charge before moving again from a stopping point.

That's more difficult to say.  Electrical heating is probably required at night.  The communications use is intermittent.  The power use for life support and communications is not that great compared to the power use for movement.  I have a mass budget of 200 kg for life support equipment.  Find a way to give me 50 kg back and you just bought yourself another 10kWh battery pack.

There is talk of Panasonic releasing new 18650 cells that up the capacity to 300Wh / kg in the near future and that means 30kWh for the same 100 kg budgeted for power storage.  I think it's reasonable to assume that that energy density will be achieved in the next ten years.  If the life support mass decreases to 150 kg and power storage mass increases to 150kg, I can't see any real requirement for more than 45kWh worth of capacity.  With 45kWh of capacity, even if life support and electrical heating consumed 1kWh, the power pack still has half of its remaining capacity available for movement.  At that point, there is a case to be made for using more powerful hub motors (4kW vs 2.5kW).

It may not be possible to move very far or fast in a dust storm, but there is still enough irradiance to provide enough power for life support.

kbd512

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Registered: 2015-01-02

Posts: 7,853

Re: kbd512 Light Presurized Rover and Habitat

Something that has been put forth before was to have drop zone cargo landers for resupply that would lighten the rover as less of the life support conditions would need to be met as we would be stopping at these sites to replentish some of what we would need rather than hauling it all from the get go...

We either successfully land four light trucks carrying everything required for a 500 day surface stay on Mars or we don't.

To reiterate, fully loaded, these vehicles have the mass and length Chevrolet Silverado 2500.  If we can't successfully land a truck on Mars, then landing a 20t to 40t habitat is pure fantasy.

We either successfully land two MAV's on Mars or we don't.

If the technology isn't ready or if the landings aren't successful, then we don't go.

This is a simple plan.  There's no reason to complicate the plan by forcing the astronauts to drive to some arbitrary location for supplies or by making the vehicles less capable of carrying the supplies that are actually required for the entire surface stay.

The only way to really explore any place is with mobility.  No sailor dead or alive ever explored any new land by tying himself to a harbor buoy.  A stationary habitat module on Mars has all the surface exploration functionality as a harbor buoy.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: kbd512 Light Presurized Rover and Habitat

Ya it will not look like this one but the numbers follow....

WheelBase = 143.5 in or 3.65 M
Overall bumper to bumper = 246 in or 6.26 M
Width = 78.5 in or 2 M
Height = 77 in or about 2 M

Since we will want this to land wheels able to engage the backshell diameter will be in the 8 M or so to get the overall length as needed to fit.

The typical ISS module is larger than what you are proposing

The 8,500-pound (3,855-kilogram) common module was not yet modified to suit astronaut housing needs aboard the ISS due to budget constraints that led station planners to pull the habitation module from the launch manifest, NASA officials added.The 29-foot (8.8-meter) long, 16-foot (4.8-meter) wide module will be connected to two others at MSFC that were designed specifically for life support system research.

The retro rocket system must fit within the remaining shape that the truck does not take up. I think that the engines could attach to the frame with the tanks to fuel them over that and to even about the trucks roof or shell that the rover would have to give the needed space to fire the engines for the required time. Some sort of landing strut would need to keep the engines and truck from being damage from the final impact of landing being probably spring or gas filled as a shock obsorber.

Once down drop a ramp to the ground, detach the engines and tanks to drive away from the landing craft. Or we could do a monstorous Skycrane.....

Not sure how well the life support will scale down to for just 1 person but I think that the following numbers might help as we would require the systems simular to the ISS example.
http://www.cnet.com/au/news/nasa-finall … naut-poop/
While we will only be capturing the sweat and urine for processing is that mass really worth the space required to recycle it as its got to be collected before we can process it even if all we do is filter and electrolysis it for oxygen and hydrogen to process the co2 out of the cabin back into oygen before wasting the methane.

http://www.livestrong.com/article/51631 … -an-adult/

The normal range for an adult urinary output is between 400 to 2,000 mL of urine daily -- with a normal fluid intake of about 2 liters per day. Values for normal urinary output may vary slightly between laboratories. A urine output of 500 mL per day is generally considered adequate for normal function

Then we will need to alicate space for exercise equipment http://science.howstuffworks.com/exercise-in-space2.htm

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: kbd512 Light Presurized Rover and Habitat

There are some more things that we may want to include in this single person home on wheels from this post...

Progress Cargo Craft Launches to Space Station, Safely in Orbit; Docking Sunday

Progress M-28M Cargo Manifest
The manifest is a table, with two tones to show summary vs detail. It's easier to read. But I'll quote the text anyway...

Refueling Propellant for Transfer to ISS Tanks     520kg    
Pressurized Oxygen for ISS Repressurization     26kg    
Pressurized Air for ISS Repressurization     22kg    
Water inside Rodnik Tank     420kg    
Total Dry Cargo Mass     1,393kg    

Atmospheric Maintenance System (gas analysis equipment, dust filters etc.)     12kg    
Water System Components (purification columns, filter, hoses, etc.)     38kg    
Sanitary & Hygiene Equipment (Russian Toilet Replaceable Parts, solid waste containers, water dispenser, wipes, etc.)     273kg    
Medical Supplies (medical aid kits, medical monitoring system, crew clothing, cleaning supplies, countermeasures, etc.)     137kg    
Food Provisions (food containers, fresh food, etc.)     430kg    
Thermal Control System (fan replacement, etc.)     10kg    
Onboard control system (Hard Drives, Cables, BSK-25B Switching Unit, etc.)     6kg    
Maintenance supplies (cargo bags, liners, window cleaning materials, etc.)     30kg    
Crew Support (flight data files,care packages for the crew, video & still cameras, etc.)     44kg    
Antenna Feeders and Installation Equipment     3kg    
Science Payloads (Microbial Control, MORZE, Regeneration, Aseptik, Kaskad, Test, Biodegradation, etc.)     21kg    
Electrical Power System Components (block 800A battery, converter/regulator, etc.)     105kg    
Onboard Telemetry Network System Hardware (Cable)     1kg    
Internal Module Outfitting Hardware (struts, handrails, hardware for MRM2, etc.)     3kg    
Zarya Module Equipment (Fire Extinguishers, Misc. Hardware)     39kg    
American Cargo for Russian Crew (food, clothing, hygiene items, crew preference items)     186kg    
American Cargo for USOS Crew (Food, Waste Disposal System Components, Hygiene Equipment, ESA Hardware)     55kg    

Total Cargo Upmass     2,381kg